1. Field of the Invention
The present invention relates to a coaxial plasma processing apparatus for etching a wafer surface with a gas that is activated by a plasma or ashing a mask remaining on a wafer surface.
2. Description of the Relevant Art
Japanese laid-open utility model publication No. 1-95730 discloses a coaxial plasma processing apparatus having an outer electrode and an inner electrode that are arranged coaxially with each other. The disclosed coaxial plasma processing apparatus has a processing chamber around which the outer electrode connected to a high-frequency power supply is disposed, the outer electrode comprising a single cylindrical member or a pair of semicylindrical members. The processing chamber houses therein the inner electrode which is electrically insulated from the outer electrode and grounded by a metallic base plate. When a high-frequency electric energy is applied to the outer electrode, a plasma is generated between the inner and outer electrodes. A reaction gas (neutral particles) is activated by the plasma and introduced through inlet holes defined in the inner electrode into the inner electrode in which wafers are placed, for thereby etching the wafers or ashing masks on the wafers.
In the conventional plasma processing apparatus, many charged particles enter a reaction region through the inlet holes in the inner electrode, developing a charge-up condition or charge buildup in the reaction region, which tends to destroy the semiconductor devices or wafers.